This invention relates to steering column arrangements for motor vehicles having a steering wheel, a telescoping steering, spindle, and a telescoping jacket tube composed of a lower part and an upper part.
In such steering column arrangements, the steering wheel is connected by way of the spindle to a steering gear, and the spindle is rotatably mounted in the tube, the lower part of the tube being supported by a lower steering column bearing on a first support component which will project into the passenger compartment in the event of a frontal collision, and the upper part of the tube being supported by an upper steering column bearing on a second support component which substantially retains its spatial position in event of a frontal collision. An unlocking device connects the second support component and the upper part of the tube and is activatable in the event of a frontal collision, and a wedge member is movable in the event of a frontal collision so as to avoid and/or diminish any upward movement of the steering wheel.
In German Offenlegungsschrift No. 44 04 375 a steering column arrangement has a wedge member which is movable so that, in the event of a frontal collision, the steering wheel will not execute any upward movement. In the event of a frontal collision, the jacket tube is telescoped, that is, the lower part of the tube is thrust toward and into the upper part of the tube. When the unlocking device is activated in a frontal collision, the upper part of the tube is, in effect, uncoupled from the second support component, that is, the positive connection between the second support component and the upper part of the tube is released. In the absence of a wedge member, the upper tube part, i.e. the upper portion of the upper part of the tube, where the steering wheel is located, would be swung farther upward when the corresponding force produced by a frontal collision is exerted the first support component through the lower part of the tube. Because of the appropriate arrangement and configuration of the wedge member, such upward movement is avoided. The wedge member is arranged so that in a frontal collision it cooperates with the unlocking device, through the upper steering column bearing, in such manner that the force emanating from the wedge surface acts to press the upper portion of the upper part of the tube, where the steering wheel is located, downwardly. In other words, the action of the wedge member causes a downward swinging movement so that, in a frontal collision, the usual upward movement is compensated.
Such conventional steering column arrangements do not have optimal configurations. In the first place, the wedge member is arranged so that, at the beginning of a frontal collision, it is not located in its operative start position, i.e. the wedge surface of the member is not in contact with the upper tube part in such manner that it will act upon it as soon as there is any displacement of the wedge member. In the second place, in one described embodiment, the wedge member is arranged so that, even when properly displaced by said first component, there is an "idle travel` between said first support component and the corresponding end portion of the wedge member. Consequently, in a frontal collision when the first support component is initially displaced, displacement of the wedge member does not occur immediately. Instead, displacement of the wedge member takes place only when the first support component strikes the end portion of the wedge member after completing the idle travel. In the conventional steering column arrangements of the prior art, the idle travel between the first component and the wedge member is utilized to activate the unlocking device. That is, during the movement of the first component through the idle travel, which may alternatively be called an unlocking travel, the unlocking device is activated, so that the upper part of the tube is uncoupled from the second support component. Then, after the uncoupling is completed upon completion of the unlocking travel, the first support component strikes the wedge member, displacing it so that upward movement of the steering wheel is avoided or diminished. Because the lower part of the tube is pushed into the upper part of the tube at the very beginning of the frontal collision, namely when the unlocking travel has not yet been completed, there will already be a slight displacement of the upper part of the tube. Furthermore, since the wedge member is not yet in its operative start position, the action of the first support component on the wedge member, after termination of the unlocking travel, prevents the wedge member, or its wedge surface, from providing the optimal action intended for it simply because, upon application of the force, the wedge surface is not properly in contact in the start position, and the upper part of the tube has already been slightly displaced, or swung. Consequently, the result is that the action of the wedge member is not optimal in the steering column arrangements of the prior art.